P0503: owner reports and bulletins

Powertrain (generic, all makes). We haven't written the explanation for this code yet. Below is what owners and manufacturers have filed with NHTSA.

Got P0503 on your scanner? Tell the mechanic your year, make, model and any symptoms and you'll get the likely cause and what to check first. Ask about this code.

What owners report to NHTSA

No consumer complaints filed with NHTSA mention P0503. That usually means it's rare, or owners don't quote the code when they file.

Manufacturer service bulletins that name P0503

4 technical service bulletins and manufacturer communications filed with NHTSA mention P0503, from 2 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:

  • CHRYSLER PACIFICA (2018), bulletin 10162529: Flash: Powertrain Control Module (PCM) Updates This bulletin involves reprogramming the PCM with the latest available software. Customers may experience a Malfunction Indicator Lamp (MIL) illumination. Upon further inves…
  • CHEVROLET CORVETTE (2015), bulletin 10113641: This preliminary informational bulletin provides a diagnostic tip for a customer concern of Malfunction Indicator Lamp (MIL) on, and technician finding DTC P0503 only set with no other symptoms.

Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.